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Investment Securities - Amortized Cost and Fair Value (Details) - USD ($) $ in Thousands	Mar. 31, 2019	Dec. 31, 2018
Schedule of Available-for-sale Securities and Held-to-maturity Securities [Line Items]
Held to maturity, Amortized Cost	$ 152,845	$ 157,206
Held to maturity, Fair Value	151,254	153,894
Held-to-maturity, Gross Unrealized Gains	300	210
Held-to-maturity, Gross Unrealized Losses	(1,891)	(3,522)
Total	442,386	465,910
Available-for-sale, at fair value	442,885	462,464
Available-for-sale, Gross Unrealized Gains	3,272	1,748
Available-for-sale, Gross Unrealized Losses	(2,773)	(5,194)
Total investment securities, Amortized Cost	595,231	623,116
Total investment securities, Fair Value	594,139	616,358
Total investment securities, Gross Unrealized Gains	3,572	1,958
Total investment securities, Gross Unrealized Losses	(4,664)	(8,716)
MBS pass-through securities issued by FHLMC and FNMA
Schedule of Available-for-sale Securities and Held-to-maturity Securities [Line Items]
Held to maturity, Amortized Cost	86,117	88,606
Held to maturity, Fair Value	84,588	85,804
Held-to-maturity, Gross Unrealized Gains	44	7
Held-to-maturity, Gross Unrealized Losses	(1,573)	(2,809)
Total	91,714	95,339
Available-for-sale, at fair value	91,771	94,467
Available-for-sale, Gross Unrealized Gains	617	358
Available-for-sale, Gross Unrealized Losses	(560)	(1,230)
SBA-backed securities
Schedule of Available-for-sale Securities and Held-to-maturity Securities [Line Items]
Held to maturity, Amortized Cost	8,403	8,720
Held to maturity, Fair Value	8,483	8,757
Held-to-maturity, Gross Unrealized Gains	80	37
Held-to-maturity, Gross Unrealized Losses	0	0
Total	48,441	50,722
Available-for-sale, at fair value	48,798	50,781
Available-for-sale, Gross Unrealized Gains	582	465
Available-for-sale, Gross Unrealized Losses	(225)	(406)
CMOs issued by FNMA
Schedule of Available-for-sale Securities and Held-to-maturity Securities [Line Items]
Held to maturity, Amortized Cost	11,166	11,447
Held to maturity, Fair Value	11,165	11,327
Held-to-maturity, Gross Unrealized Gains	0	0
Held-to-maturity, Gross Unrealized Losses	(1)	(120)
Total	27,192	28,275
Available-for-sale, at fair value	27,037	28,079
Available-for-sale, Gross Unrealized Gains	127	134
Available-for-sale, Gross Unrealized Losses	(282)	(330)
CMOs issued by FHLMC
Schedule of Available-for-sale Securities and Held-to-maturity Securities [Line Items]
Held to maturity, Amortized Cost	33,375	33,583
Held to maturity, Fair Value	33,148	33,021
Held-to-maturity, Gross Unrealized Gains	65	8
Held-to-maturity, Gross Unrealized Losses	(292)	(570)
Total	145,917	145,979
Available-for-sale, at fair value	146,237	144,836
Available-for-sale, Gross Unrealized Gains	1,112	454
Available-for-sale, Gross Unrealized Losses	(792)	(1,597)
CMOs issued by GNMA
Schedule of Available-for-sale Securities and Held-to-maturity Securities [Line Items]
Held to maturity, Amortized Cost	3,746	3,739
Held to maturity, Fair Value	3,733	3,769
Held-to-maturity, Gross Unrealized Gains	0	30
Held-to-maturity, Gross Unrealized Losses	(13)	0
Total	13,983	11,294
Available-for-sale, at fair value	13,681	11,021
Available-for-sale, Gross Unrealized Gains	0	1
Available-for-sale, Gross Unrealized Losses	(302)	(274)
Debentures of government- sponsored agencies
Schedule of Available-for-sale Securities and Held-to-maturity Securities [Line Items]
Total	37,984	52,956
Available-for-sale, at fair value	38,245	53,018
Available-for-sale, Gross Unrealized Gains	344	185
Available-for-sale, Gross Unrealized Losses	(83)	(123)
Privately issued CMOs
Schedule of Available-for-sale Securities and Held-to-maturity Securities [Line Items]
Total	251	295
Available-for-sale, at fair value	252	297
Available-for-sale, Gross Unrealized Gains	1	2
Available-for-sale, Gross Unrealized Losses	0	0
Obligations of state and political subdivisions
Schedule of Available-for-sale Securities and Held-to-maturity Securities [Line Items]
Held to maturity, Amortized Cost	10,038	11,111
Held to maturity, Fair Value	10,137	11,216
Held-to-maturity, Gross Unrealized Gains	111	128
Held-to-maturity, Gross Unrealized Losses	(12)	(23)
Total	74,902	79,046
Available-for-sale, at fair value	74,855	77,960
Available-for-sale, Gross Unrealized Gains	477	134
Available-for-sale, Gross Unrealized Losses	(524)	(1,220)
Corporate bonds
Schedule of Available-for-sale Securities and Held-to-maturity Securities [Line Items]
Total	2,002	2,004
Available-for-sale, at fair value	2,009	2,005
Available-for-sale, Gross Unrealized Gains	12	15
Available-for-sale, Gross Unrealized Losses	$ (5)	$ (14)

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